The carnage left at least 305 people dead and 128 more worshippers injured.

The adults recited their final prayers and the children howled in terror as the murderous jihadis descended on the Al Rawdaw mosque beneath an Islamic State flag.

Chilling details of the Egyptian execution that killed 305 worshipers, including 27 kids, revealed an unrelenting assault spread across 20 merciless minutes in the middle of a Friday service.

“The shooting was random and hysterical at the beginning and then became more deliberate,” said witness Edid Salem Mansour, 38, a salt factory worker hospitalized Saturday with two gunshot wounds.

“Whoever they weren’t sure was dead or (was) still breathing was shot dead.”

The unprecedented sneak attack started with a hand grenade tossed inside the house of God before shooters opened fire on the worshipers from the mosque’s front door and its dozen windows.

“Allahu Akbar!” shouted the assassins — Arabic for “God is great.”

Kids watched helplessly as the barrage of bullets killed their parents and siblings. Some inside the church stampeded toward a door leading to the bathrooms, seeking sanctuary inside.

But few found refuge as the terrorists struck without warning in the deadliest attack by Islamic extremists in Egyptian history.

The mosque’s imam had just arrived in the pulpit to start his sermon when the chaos erupted.

The killers, after spraying the house of worship with automatic rifle fire, walked methodically among the scores of bodies piled on the floor looking for survivors.

Witnesses described the terrorists firing point-blank into the heads and chests of those still breathing amid the blood and bodies.

Authorities said another 128 people were injured out of the 500 worshippers inside the mosque.

Hundreds of grieving Egyptians assembled Saturday at funerals for the victims, with President Abdel Fattah al-Sissi ordering the construction of a mausoleum in their honor.

Sheikh Sulieman Ghanem, 75, receives medical treatment at Suez Canal University hospital in Ismailia, Egypt, after he was injured during the attack.

(Amr Nabil/AP)

He also declared three national days of mourning.

The Egyptian military unleashed Saturday airstrikes and raids targeting vehicles and hideouts used by the terrorist assault teams, the president said.

All passengers inside the vehicles destroyed by Egyptian warplanes were killed, according to chief national prosecutor Nabil Sadeq. No other details were provided.

The terrorist gunmen targeted a mosque attended predominantly by Sufis, a mystic movement ostracized by other Muslim groups over the inclusion of saints and shrines in their worship.

The attackers behind the well-coordinated slaughter took up their posts at the door and the windows before the grenade blast sent the crowd in a terrified frenzy.

The jihadist killers pulled up to the church inside jeeps, wearing masks, black T-shirts and military fatigues for their murderous mission. Those without face-coverings sported thick beards and long hair, officials said.

They also carried a black banner like those carried by ISIS, with the words “There is no God but Allah and Muhammad is his prophet.”

The Islamic State did not take responsibility for the mass murder.

The attackers also set fire to seven cars outside the church to block any escape, and fired on ambulances trying to drive the wounded for medical aid.

The terrorist forces in the North Sinai had previously targeted Egyptian troops and police in the desert mountains rather than houses of worship.